1. Field of the Invention
The present invention relates generally to the field of cancer research. More specifically, the present invention relates to gene expression profiling in cancer patients.
2. Description of the Related Art
A frustrating aspect of cancer chemotherapy is the unpredictable variability of induction or duration of response and long-term survival. A significant number of patients (approximately 20%) derive no tangible benefit from the therapy, but still are subjected to drug toxicity, secondary risk, reduced quality of life, and delay in treatment that might have been effective.
Multiple myeloma is an invariantly fatal B cell malignancy that manifests at the plasma cell stage of differentiation. Although multiple myeloma initially resides in the bone marrow, it can transform into an aggressive disease with increased proliferation (resulting in a higher frequency of abnormal metaphase karyotypes), elevated LDH and extramedullary manifestations (Barlogie B. et al., 2001). Additionally, the clinical course of multiple myeloma and its response to therapy is influenced by special molecular genetic lesions and tumor cell-microenvironment interaction (Kuehl et al., 2002; Shaughnessy et al., 2003; Hideshima, et al., 2004; Fonseca et al., 2004). Although complete response can be obtained in more than 40% of patients with high-dose therapy, survival can vary from few months to more than fifteen years (Attal et al., 2003; Barlogie et al., 2004). Furthermore, high-risk disease is best captured by abnormal metaphase cytogenetics, present in 30% to 50% (DeWald et al., 1985; Smadja et al., 2001; Shaughnessy et al., 2003) of newly diagnosed patients and reflecting a higher proliferative capacity and stromal cell-independence of the malignant clone. However, karyotypes of multiple myeloma are notoriously complex and have until recently defied cytogenetic classification. Nevertheless, a comprehensive correlative analyses of multiple myeloma karyotypes with patient survival from multiple laboratories now reveal that hyperdiploid, non-hyperdiploid, chromosome 13 deletion-positive, t(4;14)(p16;q32)-positive, and t(11;14)(q13;q32)-positive forms of the disease likely represent unique subclasses with divergent clinical outcomes.
While the presence of an abnormal karyotype has emerged as the single most significant prognostic variable in predicting outcome in patients receiving high dose chemotherapy and tandem stem cell transplants, this variable in combination with other historically relevant clinical parameters, e.g. serum albumin, b2M, and lactate dehydrogenase, account for no more than 30% of the variability in outcome in this disease. Thus, there is a need for more robust risk stratification algorithms for this disease.
Multiple myeloma is characterized by complex karyotypes and chromosome 1 instability at the cytogenetic level. Chromosome 1 instability generally involves partial duplications, whole-arm translocations or jumping translocations of 1q identified by G-banding. This instability was further characterized recently using a combination of spectral karyotyping and fluorescence in situ hybridization (FISH) with probes for satII/III (1q12), BCL9 (1q21), and IL6R (1q21) on the karyotypes of 44 patients with known 1q aberrations (Sawyer et al., 2004). In eight patients segmental duplication of 1q12-21 and adjacent bands occurred on non-homologous chromosomes. In five cases, the 1q first jumped to a non-homologous chromosome, after which the 1q12-21 segment subsequently again duplicated itself one to three times. In three other cases, segmental duplications occurred after the 1q first jumped to a non-homologous chromosome and then duplicated the adjacent proximal non-homologous chromosome segment prior to jumping or inserting to a new location. These cases demonstrate that satII/III DNA sequences are not only associated with duplication of adjacent distal chromosome segments after translocation, but are also associated with duplication and jumping/insertion of proximal non-homologous chromosome segments (Sawyer et al., 2004).
In B-acute lymphoblastic leukemia and many other advanced neoplasia, extra copies of 1q may confer a proliferative advantage on the tumor cells. Currently, the ultimate molecular target(s) of the 1q21 amplification and jumping in 1q in myeloma and many other cancers is not known. The prior art is thus deficient in providing a chromosome 1 marker(s) or a chromosome 13 marker(s) useful for initial staging as well as disease follow-up for multiple myeloma and other types of cancer. The present invention fulfills this long-standing need and desire in the art.